Domesticated animal injuries and the widespread suffocation of native plants throughout the Hawaiian islands is often the result if the Yellow Himalayan Raspberry is left unchecked.
By Damon Adamson.
Native to the continent of Asia and surrounding islands (Tropical China, India, Sri Lanka, and the Philippine Islands), the Yellow Himalayan Raspberry (Rubus ellipticus) was introduced to Hawaiʻi in 1960 for its edible fruit and ornamental purposes, but rapidly escaped cultivation in 1961 and is now thoroughly documented on the island of Hawaiʻi. At present, the greatest infestation on Hawaiʻi is centered in the Volcano community adjacent to Hawaiʻi Volcanoes National Park, and many mid-elevation forests (1060-1200 m).
This plant is a perennial that can be propagated through vegetative means and by direct seeding. It is a stout, evergreen shrub measuring 1-3m in height. It has purplish red branchlets with sparse curved prickles and dense, purplish brown bristle hairs, three-foliolate leaves imparipinnate with a petiole size of (2–6 cm).
The leaflet blade is elliptic or obovate (4–8cm × 3–6cm) terminal leaflet much larger than lateral leaflets, purplish red bristles along prominent veins, margin unevenly minute sharply serrate, apex acute, abruptly pointed, shallowly cordate, or sub-truncate. It has an inflorescences terminal and dense glomerate racemes. Flowers of white or pink measure (1-1.5cm) in diameter grow vigorously in clusters at leaf axils.
R. ellipticus reproduces readily by seed, which, when carried by fruit-eating birds, are its primary means of long-distance dissemination.
Flowers are hermaphrodite and are pollinated by insects. New stems are produced each year from perennial rootstock.
The plant spreads rapidly by root suckers and regenerates from underground shoots after fire or cutting. A rapid growth rate in tropical mid to lower elevations allows for dense thickets of R. ellipticus to develop. Pasturelands and recently disturbed forests are particularly susceptible to the large and dense thickets.
Domesticated animal injuries and the widespread suffocation of native plants throughout the Hawaiian islands is often the result if left unchecked. In South Africa, R. ellipticus was recorded for the first time in August 2013. In Australia, first reports of it having naturalized were in 1912 in Queensland, where it has since been declared noxious.
In Hawaiʻi, the species has been controlled mechanically in pastures by chopping out or bulldozing. In Hawaiʻi Volcanoes National Park, cut stem treatments with herbicides were found to be most effective at controlling R. ellipticus var. obcordatus on a local basis. However, the aggressiveness of this plant in Hawaiʻi and its ability to become widely disseminated suggest that the only practical approach will be biological control. Chemical control methods for Rubus spp. include foliar, stem injection, cut stump and basal stem methods using glyphosate or triclopyr products.
Biological control has been studied in China around 2010 resulting in two moth species being identified as viable, Epiblema tetragonana and Epinotia ustulana, have been found to have a narrow host range and to be widely distributed in Yunnan, China.
Damon Adamson (senior, horticulture) received a bachelor of arts in history from UH West O‘ahu. He is retired U.S. Army, born in San Diego, CA.